diff --git a/src/os.c b/src/os.c
index fc971a44..e01d9d97 100644
--- a/src/os.c
+++ b/src/os.c
@@ -68,9 +68,12 @@ static void* mi_align_up_ptr(void* p, size_t alignment) {
 static inline uintptr_t _mi_align_down(uintptr_t sz, size_t alignment) {
   mi_assert_internal(alignment != 0);
   uintptr_t mask = alignment - 1;
-  if ((alignment & mask) == 0)  // power of two?
-    return sz & ~mask;
-  return (sz / alignment) * alignment;
+  if ((alignment & mask) == 0) { // power of two?
+    return (sz & ~mask);
+  }
+  else {
+    return ((sz / alignment) * alignment);
+  }
 }
 
 static void* mi_align_down_ptr(void* p, size_t alignment) {